"Carbon dioxide is a greenhouse gas. When you put more of it in the atmosphere, the radiation budget will respond appropriately. It's just that what we found with the real data is that the way the earth responds is to shed a lot of heat, not keep it in which the climate models do. So I'd rather base policy on observations than on climate models. Where is the biggest response to greenhouse gases? It's in the atmosphere, not on the surface. So if you want to measure the response and say that's the greenhouse gas response, you would look in the atmosphere. That's precisely where satellites measure it." University of Alabama scientist, Dr John Christy, with his colleague Dr Roy Spencer, answer questions about their 25 years studying climate changes.